Tarta De Almendras (Almond Tart)

From Teresa Barrenechea in The Basque Table:
When she was asked to be the guest chef for a meal honoring Sr. Alvarez del Manzano, the mayor of Madrid, at the Biltmore Hotel in Los Angeles, the menu included this classic Spanish tart. It is so rich and moist, it needs no more garnish than a little Basque Cream (Natillas) Dessert Sauce (pouring custard) and a dusting of powdered sugar.
Marcona almonds are commonly found in Spain and are a bit richer in flavor and sweeter: lightly roasted in oil and then ground, they will ad much to this dish's subtle flavors. Buy raw almonds, if possible. Because you will be grinding the nuts, it doesn't matter whether they're whole or sliced when you buy them.